Two-amplifier recording and reproducing phonograph



15, 1946. L :THOMP$ON 2,409,520

TWO-AXVIPLIFIER RECORDING AND REPRODUCING PHONOGRAPH Filed Feb. 12, 1944 4 Sheets-Sheet 2 Star? of giant of Paar-072315 .flgyZus 53 Pzayaach' sgylus 54 35 Spacing of 3-4grquas Beizveen Pqcoralzny and Playback Sgy'luacs IN VEN TOR. Lin C0271 Thompson TWO-AMPLIFIER RECORDING AND REPRODUCING PHONOGRAPH L. THOMPSON Filed Feb. '12

4 Sheets-Sheet 4 Patented Oct. 15, 1946 TWO-AMPLIFIER RECORDING AND REPRO- DUCING PHGNOGRAPH Lincoln Thompson, Cheshire, Conn, assignor to The Sound Scriber Corporation, New Haven, Conn, a corporation of Connecticut Application February 12, 1944, Serial No. 522,113

1'7 Claims. 1

This invention relates to phonographs, and

recording dictating machine with selective playback.

One object of this invention is to provide a dictating machine of the above nature employ ing a microphone, and a unitary control handle provided with switches for starting and stopping the record, selecting between recording and playback, indicating corrections, and adjusting the sensitivity of the microphone.

A further object is to provide a machine of the above nature in which means are provided for automatically starting the recording stylus on the record a predetermined number of grooves ahead of the playback stylus.

A further object is to provide a machine of the above nature in which both the playback stylus and recording stylus will be in continuous contact with the record from the beginning to the end of the groove formed thereon.

A further object is to provide a machine of the above nature having means to produce a special signal on the groove for indicating to the transcribing operator when the recorded material was being played back by the person dictating.

A further object is to provide a device of the above nature which will be simple in construction, inexpensive to manufacture, easy to install and manipulate, compact, ornamental in appearance, and very eficient and durable in use.

With these and other objects in view, there have been illustrated on the accompanying drawings several forms in which the invention may conveniently be embodied in practice.

In the drawings,

Fig. 1 represents a circuit diagram of the first form of the invention.

Fig. 2 is a perspective view of a handle containing the microphone and loudspeaker, and the switches for controlling the machine.

Fig. 3 is a side view of the same.

Fig. 4 is a top plan view of the dictating machine showing the relative positions of the recording and playback arms at the beginning of the groove.

Fig. 5 is a plan view of a disk phonograph record mounted upon a turntable and showing the initial staggered relationship of the record ing and playback styluses which is maintained throughout the recording.

Fig. 6 is a perspective view, on an enlarged scale, of the playback head stop member.

Fig. 7 is a circuit diagram of a second form of the invention, showing an additional switch out waste of time.

for indicating corrections on the disk record, and also showing a combined microphone and loudspeaker unit.

Fig. 8 is a perspective view of the control handle for the same.

Fig. 9 is a circuit diagram of a third form of the invention, having two buzzers, one of which impresses on the record a signal indicating playback, and the other a different signal indicating corrections.

Fig. 10 is a chart illustrating an example of how the third form of the machine may be used.

The present machine is designed to employ separate playback and recording amplifiers in order to be able, selectively, to record a sound groove upon the record, or reproduce from a previously recorded groove, without removing the recording stylus or reproducing stylus from said record.

It is also a featutre of the present invention to provide means to produce a characteristic tone on the record groove to warn the transcribing operator that playback has taken place so that the stenographer transcribing the record may skid the reproducing stylus forward to a point on the record where the identifying tone is. absent with- A continuous groove is formed on the record by the recording stylus, and transcription is thereby facilitated because of the elimination of gaps in the groove, thus avoiding any tendency for the pickup to repeat the last grooves of previously recorded material, which would require the skidding of the pickup stylus forwardly to the next groove.

Referring now to the drawings in which like reference numerals denote corresponding parts throughout the several views, the numeral It] indicates the cabinet of a dictating machine having a turntable l l upon which is mounted a fiat disk record tablet I2 which is centralized thereon by means of a spindle l2a having a square upper end. Provision is made on the right side of the record l2 (as viewed in Fig. 4) of a recording arm l3 which is swung at constant speed across the tablet by means of a driving shaft M, the latter having a pulley l5 rigidly mounted on the upper end thereof.

At the left hand side of the cabinet, provision is made of a playback arm [6 pivotally mounted on a shaft l8 which has on its upper end an adjustable pulley ll of the same diameter as the pulley l5. The pulley I1 is driven positively from the pulley i5 by means of a crossed feed cable 59, whereby the speed of the playback arm it across the tablet 12 will be identical with that of the recording arm [3.

A playback head 24 is loosely mounted with a small lateral backlash in a forked end 23 of the playback arm I 6. A recording head 2| is mounted in a forked end of the arm I5. The recording and playback heads, 2i and 24, are both pressed downwardly against the record tablet by means of coiled tension springs 22, attached to the recording arm I3 and playback arm l6, respectively, as clearly shown in Fig. d.

Provision is also made of yokes, 26, 2'! surrounding the recording head 2! and the playback head 24, respectively, as clearly shown in Fig. 4. Moreover, in order to facilitate manipulation, the recording head 21 and playback head 24 are also provided with forwardly extending handles 21a, 21b respectively.

In order to provide for a definite starting position for the recording arm 13, provision is made of an adjustable angle stop member 28 located on the cabinet I0 adjacent the fork 20. The angular stop 28 is adapted to be adjusted by means of a screw 29 and a lock nut 29a.

The playback arm is is also provided with an adjustable angle stop 39 located outside of the fork 23, and said stop 30 has an adjusting screw 31 and lock nut 32. The stops 28 and should preferably be so adjusted that when the arms 13 and I5 are swung outwardly against said stops the playback stylus will be positioned (or sta gered) a definite number of grooves behind the recording stylus (three in this instance). Moreover, since the playback head 24 has a certain amount of lateral backlash in its bearings, it is necessary to provide an additional angle stop 33 to positively position said head 24. The stop 33 has a slot 34 in its base for receiving an adjusting screw 35, and a hole 35a for a screw upon which it may pivot.

Referring now to the circuit diagram shown in Fig. l of the drawings, the numerals 36, 31 represent a pair of conductors leading from a turntable motor 38. The conductor 37 leads directly to a two-prong power plug 39 adapted to be connected to a source of alternating current. The conductor 35 leads to a fixed contact 39a of a motor switch A, which contact is adapted to be engaged by a movable switch arm 40 connected by a conductor 4! to the power plug 39. A pair of conductors 42, 33 lead from the recording head 2! to a recording amplifier 34. A pair of conductors 45, 46 connect the playback head 24 to a playback amplifier 41.

The dictation or other sounds to be recorded are adapted to be received by a microphone 48 having conductors 49, 5% leading therefrom. The conductor 50 is connected by a conductor 5| to a conductor 52 which connects the amplifiers s4 and 47. The conductor 49 is connected to a movable contact lever 53 of a sensitivity switch C, and said lever 53 is adapted to be swung between a pair of fixed contacts 55, 55 in order to select between conference and close dictating positions. A conductor 56 leading from the contact 55 includes a resistance 55a and is connected to a fixed contact 51 of a switch B for selecting between recording and playback. A conductor 58 connects the contact 54 to the conductor 56.

A movable two-pole switch member 59-63, when closed, is adapted to engage a pair of stationary switch contacts 6!, B2 of the switch B. The pole 59 is connected by a conductor $3 to the input of the recording amplifier 44, while a conductor 64 connects the pole 65 to the output of the playback amplifier 41.

The output of the playback amplifier 41 is adapted to be emitted by a loudspeaker 65 (or headphone) which is connected by a conductor 56 to the contact 82. A conductor 67 also connects the loudspeaker to the conductor 5|.

The numeral 68 indicates a buzzer which is connected by a conductor 69 to the contact 6|. The numeral 19 indicates a conductor leading from the buzzer 63 to the conductor 52.

As clearly shown in Figs. 2 and 3 of the drawings, a control handle I! is provided having a reduced bottom section 72 containing switch arms 53, 59-55, and 45, and said section 12 is connected to a cord 13 leading to the circuits of the apparatus.

Operation In the operation of the first form of the invention, the dictators procedure in starting to record, is to lower the recording head 2| upon the record [2 and press said head outwardly against the stop 23. The playback arm l5 and head 24 will then be lowered upon the record and also pressed against the stops 3G and 33, so as to position the playback stylus a predetermined number of grooves behind the recording stylus (herein shown as three grooves, see Fig. 5). The dictator then proceeds to talk and if he is interrupted and wishes to refresh his mind with the material he has already dictated, it will be merely necessary for him to press the movable poles 5960 of the switch B against the fixed contacts GI, 62, which will cause said material to be played back through the loudspeaker 65.

During the playback the recording stylus will merely form a continuous groove in the record without undulations.

It will also be understood that during playback periods, the buzzer 68 will actuate the recording stylus to produce a characteristic buzzing tone in the record groove. This will permit the transcribing operator to skid the reproducing stylus forward across the record, until the buzzing tone disappears.

Second form of invention In the second form of the invention illustrated in Figs. 7 and 8, the numeral Ill] indicates a turntable motor which is connected b a conductor ill to a fixed contact H4 of a motor switch A, having a movable contact H5 for engaging said contact i 6.

The numeral H2 indicates a conductor connecting the turntable motor illl to a two-prong plug H3, which is adapted to be connected to a source of alternating current.

A conductor H5 connects the movable contact i it with the two-prong plug I [3.

In this form of the invention, provision is made of a recording amplifier H? which is connected by a pair of conductors I I8, H9 to the recording head 2! so as to apply the output of the recording amplifier II'i' upon the recording stylus. A playback amplifier 52B is also employed, and is connected by a pair of conductors I21, I22 to the playback head 24, the stylus of which (as in the first form of the invention), is adapted to be spaced three grooves behind the recording stylus.

A combined interchangeable microphone and loudspeaker I23 is employed in this form of the invention, and is connected by a conductor I24 to a conductor which connects the recording amplifier II! to the playback amplifier I20.

In order to control the sensitivity of the microphone, so as to permit conference recording or close recording, as desired, provision is made of a control switch C having a movable contact I26 which is adapted to be swung between a pair of fixed contacts I21, I28. The combination microphone and loudspeaker I23 is connected by a conductor I29 to the contact I26 of the control switch C.

The numeral I 33 indicates a resistance connected to the fixed contact I28 and said resistance is connected by a conductor I3I to the fixed contact I21,

In order to permit the apparatus to be instantly shifted from recording to playback, and vice versa, provision is made of a selective switch B, having three fixed contacts I32, I33, I34, which are adapted to be engaged by a manually-operated mechanically connected two-pole movable switch contact member I35-I36, as shown in Fig. 7.

The following connections are also provided in the circuits: The contact I32 is connected to the conductor I3I by a conductor I31. The conductor I 29 is connected to the contact I34 by a conductor I33. The movable contact I35 is connected to the input of the recording amplifier I I1 b a conductor I39. The movable contact I36 is connected by a conductor I39a to the output of the playback amplifier I26.

The numeral I40 indicates a buzzer which is adapted to be impressed automatically upon the recording head, through the recording amplifier, whenever the switch B has been manually closed for playback.

The buzzer I40 may also be employed to produce a momentary characteristic tone in the groove being recorded for indicating corrections. For this purpose, provision is made of a switch D having a movable contact arm I4I which is urged by a spring I42a to open position, When the switch I4! is manually closed, it will engage a fixed contact I42, which is connected to the buzzer I46 by means of a conductor I43,

The buzzer I46 is also connected to the conductor I25 by a conductor I44, The movable contact I35 of the switch B is connected by a conductor I45 to the movable contact *I4I of switch D, and the fixed contact I33 of switch B is connected to the conductor I43 by a conductor 145a.

As shown in Fig. 8, a control handle I46 is employed having a reduced lower end I41 connected to the circuits of the apparatus by a cord In the operation of the second form of the invention, it will be understood that a prolonged buzzing will be impressed in the groove during playback period when the switch B is closed, while a short buzzing signal will be impressed on said groove to indicate corrections, when the switch D is momentarily actuated.

Third form of invention In the third form of dictating machine illustrated by the circuit diagram of Fig. 9, the numeral 256 indicates a turntable motor which is connected by a conductor 2II to a stationary switch contact 2M of the motor switch A. The turntable motor 2I0 is also connected by a conductor 2H2 to a two-prong plug 2I3 adapted to be connected to a source of alternating current.

The numeral 2I5 indicates a manually-operated movable switch contact which is connected by a conductor M6 to the two-prong plug 2I3.

The third form of dictating machine is provided with a recording amplifier 2I1 having output terminals connected by conductors 2I8, 2I9

to the recording head 2|. A playback amplifier 220 is also provided, being connected by a conductor 22I to the playback head 24, as clearly shown. Provision is also made of a combination interchangeable microphone and loudspeaker unit 222, similar to the unit I23 of the second form.

In order to control the sensitivity of recording, provision is made of a switch C containing a movable contact 224 and a pair of fixed contacts 225, 226, respectively, located on either side of .said movable contact 224. Provision is also made of a resistance 221 connected to the fixed contact 226, and a conductor 228 for connecting the resistance 221 with the contact 225. The movable contact 222 is also connected by a conductor 229 to the combination microphone and loudspeaker unit 222.

A conductor 236 is also provided to connect the recording amplifier 2I1 to the playback amplifier 226. A conductor 23I connects the unit 222 to the conductor 230.

Provision is made of a selective switch B to permit rapid shifting between recording and playback as desired, which includes three fixed contacts 232, 233, 234 and a two-pole movable contact member 235236, the poles of which are mechanically joined so that they will move in unison when manually operated.

The contact 232 is connected to the conductor 223 by means of a conductor 231. The conductor 229 is connected to the contact 234 by a conductor 233. The pole 235 of the switch B is connected by a conductor 239 to the input of the recording amplifier 2I1, while the pole 236 of said switch is connected by a conductor 239a to the output of the playback amplifier 220.

In order to indicate corrections upon the recorded groove, provision is made of a correction switch D-E which employs a movable two-pole contact member 24l242, the poles of which are joined together mechanically so as to swing in unison. and the movable poles 24 I242 are maintained normally in open position by means of a spring 242a. The poles 24I-242 are adapted to engage fixed contacts 243, 244, when manually swung to closed position. The fixed contact 233 is connected to a buzzer 24!] (B1) by means of a connector 245, and the conductor 236 is connected to said buzzer by means of a conductor 246.

Other circuit connections are as follows: The fixed contact 243 of the switch DE is connected to a high-pitched buzzer 241 (B2) by means of a conductor 248. The conductor 230 is connected to the buzzer 241 by a conductor 249. The movable contact 242 of the switch D-E is connected to the input of the playback amplifier 22!] by a conductor 256. The fixed contact 244 of the switch DE is connected by a conductor 25I to the conductor H8. The playback head 24 is connected by a conductor 252 to the movable pole 242 of the switch D--E.

The operation of the third form of the invention is indicated by the chart shown in Fig. 10. In this chart, the numeral 253 indicates the continuous spiral groove formed in the record, and the numeral 254 the numbers of the successive groovesforty of which are herein shown.

The numeral 255 indicates that talk occurred in the first five grooves (Nosv 1-5). The numeral 255 indicates that the first five grooves were then 7 played back to refresh the memory of the dictator, as shown on the chart by means of a wide vibratory band produced by the buzzer 246 (B1) a prolonged characteristic tone extending from grooves Nos. 6-10. being thus produced. The numeral 251' indicates the groove II, at which further. dictation occurred. The numeral 258 indicates a correction signal (at groove No. 12) from. the lower pitch buzzer 24 8 (B1) produced bythe recording stylus 2i, and the numeral 259 indicate a weaker correction signal produced by the, playback stylus three grooves behind the signal-258, (groove No. 9) from energy supplied to the playback head 2G from the recording amplifier 21?, which causes said stylus to act to some extent as arecording stylus. The signal ZEiiwill, of: course, be superimposed upon the buzzer tone 256.. previously recorded.

The; numeral 265, indicates eight grooves (Nos. l3-.-20) of, further dictation. The numerals 26L 262 indicatecorrection signals produced simultaneously from the buzzer 241 (B2) by the recordin ihead 2i and, the playback head 24, respectively, at grooves Nos. 21 and 18, said signals being spaced three grooves apart, as before. The numeral 253 indicates nine grooves of dictation (Nos. 2230). The numeral 254 indicates four grooves (Nos. 31-34) of playback signal from the buzzer 246 (Bi), and the numeral 265 indicates the: final dictation of six grooves (Nos. 35- 10) as made by the recording head 2!.

In'the operation of the third form of the invention it will be seen that three different types of signals are given. First; the low pitched buzzer 243 (B1) will be impressed upon. the spiral groove by the recording head 21 by the switch B during playback periods, when playing back previous dictation. Second; the higher pitched buzzer 2 H-- (132) will be impressed upon the groove by the, recording head 2! momentarily by the switch D during short pauses in the dictation. Third; at the same time that the second signal i given, the-playback head 24 will be energized momentarily bythe recording amplifier 2H to indent a fainter buzzer signal three grooves behind the recording stylus.

While there have been disclosed in this specification several forms in which the invention may be embodied, it is to be understood that these forms are shown for the purpose of illustration only and that the invention is not to be limited to the specific disclosures, but may be, modified and embodied in various other forms without departing from its spirit. In short, the invention includesall the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is, claimed as new and for which it is desired to.

secure Letters Patent is:

1. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a stylus-carrying recording headv connected to theoutput of saidamplifier for producing, a. continuous groove on said record, a stylus-carrying playback head resting in said groove, an amplifier for the energy reoeivedby said, playback head, a loudspeaker connected to.

start:v the recording stylus a predeterminednumber of grooves ahead of the playback stylus.

4. A dictating machine as set forth in claim 1, in which stop-means are provided to position the recording stylus a predetermined number of grooves ahead of the playback stylus when the respective recording arm and playback arm are swung against said stop means.

5. In adictating machine, a cabinet, a moving disk record mounted in said cabinet, a recording means and a playback means mounted to move across said record, and individual stop members mounted on said cabinet adjacent the opposite edges of said record, against which each of said means are adapted to be, swung at the startof the recording to fix the position of. said playback means a predetermined number of grooves behind the position of said recording means.

6. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a stylus-carrying recording head connected to the output of said amplifier for producing: a continuous groove on said record, a stylus-carrying playback head resting in said groove, an amplifier for the energy received by said playback head, a loudspeaker connected to the output of said playback amplifier, means to switch-the connections of said machine selectively from recording to playback, means to automatically. record a prolonged characteristic tone in said. groove during playback periods, and manwilly-operated means to record a characteristic tone insaid. groove to indicate when a correction is needed.

7.. The invention as defined in claim 6, in which a buzzer is provided for producing said characteristic tone;

8. In a dictating machine, a moving record, a microphone, an amplifier. connected with said microphone, a stylus-carrying recording head connected to the output of said amplifier for producing a continuous groove on said record, a stylus-carrying playback head resting in said groove, an amplifier for the energy received. by said playback head, a loudspeaker connected to the output of said playback amplifier, means to switch the connections of said machine selective- 1y from recording to playback, means to automatically record. a prolonged characteristic tone in said groove during playback periods, and manually-operated means. to cause said recording stylus to produce a characteristic tone in said groove to indicate'whena correction isneeded.

9. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a. stylus-carrying recording head connectedto theoutput of said amplifier for, producing a continuous groove on said record, a stylus-carrying playback, head, resting in said groove, an amplifier for the energy received by said playback head, a loudspeaker connected to the output of said playback. amplifier, means to switch the connections ofsaid machine selectively from recording to playback, means to automatically record a prolonged characteristic tone in said groove during playback periods, and manually-operated means to cause said playback stylus to record a characteristic tone in said groove to indicate-when a correction is needed.

10. In a dictating machine, a moving record, a stylus-carrying recording head, and a stylus-carrying playback head mounted to move-across said.

record, means to. cause both of said Styluses to remain in continuous, contact with said record.

and to be spaced a predetermined number of,

grooves apart throughout the length of the groove formed thereon, and means to cause both of said styluses to record signals in said groove simultaneously to indicate when a correction is needed.

11. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a stylus-carrying recording head connected to the output of said amplifier for producing a continuous groove on said record, a stylus-carrying playback head resting in said groove, an amplifier for the energy received by said playback head, a loudspeaker connected to the out put of said playback amplifier, means to switch the connections of said machine selectively from recording to playback, means to automatically record a prolonged characteristic tone in said groove during playback periods, and manually-operated means to cause said recording stylus to produce a difierent characteristic tone in said groove to indicate when a correction is needed.

12. In a dictating machine, a moving record, a stylus-carrying recording head and a styluscarrying playback head mounted to move across said record, means to cause both of said Styluses to remain in continuous contact with said record and to be spaced a predetermined number of grooves apart throughout the length of the groove formed thereon, and means to cause both of said styluses to record signals in said groove simultaneously to indicate when a correction is needed, both of said correction signals being actuated by a single buzzer connected to said recording amplifier.

13. The invention as defined in claim 6, in which the playback signal and the correction signal are energized by two separate buzzers which produce difierent tones.

14. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a holder for said microphone, a recording head connected to the output of said amplifier for producing a continuous groove on said record, a pickup head also resting in said groove, a listening device also carried by said holder and electrically connected with said pickup, means on said holder to switch the connection of said machine selectively from recording to playback, and means to cause said recording head to automatically record a characteristic signal in said groove during playback periods.

15. The invention as defined in claim 14, in which said recording head is adjusted to continuously record on said record at a point spaced a predetermined number of grooves ahead of said pickup head.

16. In a dictating machine, a moving record, a microphone, an amplifier connected with said microphone, a stylus-carrying recording head connected to the output of said amplifier for producing a continuous groove on said record, a stylus-carrying playback head resting in said groove, an amplifier for the energy received by said playback head, a loudspeaker connected to the output of said playback amplifier, means to switch the connections of said machine selectively from recording to playback," means to automatically record a prolonged characteristic tone in said groove during playback periods, and manually-operated means to record a signal in said groove to indicate when a correction is needed.

1'7. The invention as defined in claim 6, in which the playback signal and the correction signal are energized by two separate signals which produce difierent tones.

LINCOLN THOMPSON. 

